Skip-stitch sewing machine



L. Raw/ERS SKIP STITCH SEWING MACHINE Filed Aug. 22, 1935 S R E W AWM I SKIP STITCH SEWING MACHINE Filed Aug. 22, 1935 ATTCRNEYS L. IRM/ERS SKIP STITCH SEWING MACHINE www 9 I M Filed Aug. 22, 1935 4 Sheets-Shaw, 3

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INVENTOR AToRNEYs L. @ux/ERS SKIP STITCH` SEWING MAC`HINE Filed Aug. 22, 1935 4, sheets-sheet 4 eww ATTORNEYS' Patented Apr. 7, 1936 UNITED STATES PATENT OFFICE SKIP-STITCH SEWHNG MACHINE Application August 22, 1935, Serial No. 37,288

5 Claims.

The present invention relates to improvements in the type of machines disclosed in Charles A. Dearborn Patent No. 2,000,929 granted May 14, 1935 for work supporting means for sewing machines. The mechanism of this patent was designed for producing a succession of Widely spaced deep stitches with one or more shallow or skipstitches between successive deep stitches, the result being accomplished by intermittently lowering the yieldingly mounted work-supporting frame carrying the ridge-forming member which moves in unison therewith and preferably oscillates back and forth beneath and across the path of the needle.

In this Dearborn type of blind stitch sewing machine the yieldingly mounted work-support is constructed to yield to permit its manual depression for the insertion and removal of the work between it and a stationary presser-foot, and to automatically yield to the eXtra downward pressure caused by the passage of an eXtra thickness in the work such as in crossing seams.

In the mechanism of the above-named patent the change from deep to shallow or skip-stitches is eifected by an automatic mechanism that periodically lowers and raises the work-supporting frame and ridge-forming member carried thereon,-(said ridge-forming member and frame being unyielding relatively and therefore moving in unison toward and away from the presserlfoot) ,-so that the thickness of the bight of material presented to the needle will vary according to the height of the active part of the ridgeforming member (determined by the height of the work-supporting frame) at the moment the needle penetrates the work. While this mechanism has been successful in operation it is mechanically objectionable to continually rock the work-supporting frame for lowering and raising the ridge-forming member, because of the wear and tear upon the mechanism which is under very heavy spring pressure and is normally run at very high speed, and also because of the annoying vibration of the work and the hands of the operator directing the work.

To this end the present invention has for its object the production of a machine of the general type referred to for performing skip-stitch work without the objectional periodic movement of the work-supporting frame.

In the present invention (the spring sustained. work-supporting frame may still be manually lowered for the insertion and remo-val of work),

the ridge-forming member is mounted upon an auxiliary frame which extends beneath and is movably mounted upon the work-supporting frame; said auxiliary frame forming no part of the work-support and being itself yieldingly held in position upon the wo-rk-support by a relatively light independent spring. With this arrangement the ridge-forming member moves independently oi and upon the work-supporting frame and is periodically and automatically actuated by a suitable mechanism to raise and lower it with reference to the stationary presser-foot in timed relation with the stitch-forming mechanism to produce the desired succession of spaced deep stitches and the intervening shallow or skipstitches. The number of shallow or skip-stitches between successive deep stitches is determined by the gear ratio of the operating mechanism as in the above-named patent. With this new arrangement the independently movable ridgeforming member will also move with the worksupporting frame when it yields automatically to the pressure of an increased thickness of a seam passing between it and the presser-foot, and also when the work-supporting frame is manually depressed for the insertion and removal of Work. The auxiliary frame carrying the ridge-forming member is preferably normally held by its spring in its low position upon the work-support for making blind or skip-stitches, and its operating mechanism periodically raises the auxiliary frame to high position to produce the spaced deep stitches. The light spring sustaining the auxiliary frame of the ridge-forming member yields more readily to its operating mechanism than formerly did the whole work-supporting frame with its more powerful sustaining spring. In the new arrangement less power is required and there is less wear and tear upon the machine in operating the independently movable ridge-forming member.

In order that the invention may be fully understood it will rst be described with reference to the accompanying drawings and the novelty afterwards pointed out more particularly in the annexed claims.

In said drawings Figure 1 is ya plan View of the improved machine embodying the present invention, parts being broken away for the sake of clearness;

Figure 2 is a side elevation of the same;

Figure 3 is a vertical longitudinal sectional View taken on the line 3-3 of Figure l;

Figure l is a detail vertical transverse sectional view taken on the section line ffl- 4 of Figure 3;

Figure 5 is a View similar to Figure 3 showing the parts in a slightly changed position; and

Figures 6 and 7 are detail sectional views illustrating different phases of the work performed by the improved machine.

The main frame of the machine of the type to which the present improvements are particularly applicable is formed of a single heavy casting having integral strengthening ribs and comprising essentially a rigid central base I, centrally perforated for rigid bolting to a work bench, the upwardly extending main arm 2 at the rear terminating in the shaft bearing sleeve 3 from the left of which projects the forwardly extending arm 5 having horizontal bearings for the usual needle rock-shaft. This forward machine arm 5 also supports the looper and feed bar in the wellknown manner.

Extending forwardly and upwardly from the front of base l is the integral arm 6 terminating in the sleeve 'I in which is secured the front horizontal bearing shaft or rod 8 upon which is pivoted the work-support lli), presently to be described.

IB is the main driving shaft of the machine journalled in the sleeve bearing 3 of the rear arm 2 and having secured at one end the combined driving pulley I I and fly-wheel I2.

The forwardly extending needle rock-shaft journalled in the framev bearings has rigidly mounted upon its forward end the needle carrying rock-arm I5 in which is mounted the usual curved needle I'I. The machine is provided with the usual thread guides and tension devices which form no part of the present invention and are therefore not referred to in detail.

The operating mechanism for the needle rockshaft is the same as in the well-known Dearborn type of blind stitch sewing machines.

40 is the work supporting frame formed with the spaced bearing sleeves fil which are freely journalled upon the oppositely projecting ends of the rod or shaft 8 carried in sleeve l in the upper end of frame arm B. These bearing sleeves 4I rest snugly against the finished vertical side faces of the sleeve 'I which they embrace. Projecting downwardly from one of the bearings 4I is an integral rock-arm 112 engaged at its lower end by a heavy coil spring 43 which extends rearwardly from said arm 42 to one arm of a stout horizontal bell crank lever 44 which is pivoted at 45 to the base i. The other arm of bell crank 54 is engaged by an adjustable screw stop 46 threaded through the strengthening rib Ia of the base frame, the described arrangement giving to the pivoted cloth-supporting frame 40 a strong spring support to hold it in its normal horizontal working position, which is determined roughly by any suitable adjustable screw stop upon the machine frame.

The depression of the work-supporting frame for placing the work upon the frame-horn beneath the presser-foot is accomplished by the usual treadle I5 connected by a chain or wire 15a with a link ida hooked to the rear e-dge of frame 40.

The work supporting frame 4t is extended to the left to form a work-supporting horn as is usual with this type of machine.

An auxiliary skeleton frame 50 is journalled at its ends 50a upon conical bearing screws 5I threaded through the opposite ends of the main work-supporting frame 40. This auxiliary frame has journalled init, upon the usual conical bearing screws 55, the oscillating shaft 5I which carries the fulling in ridge-forming rib or disk 60 of the usual construction. The usual independently yielding work supporting plates or platens 'l0 are mounted upon opposite sides of the ridge-forming disk 60, each plate 'i0 being pivoted upon an arm or lever pivoted upon work-supporting frame l0 and provided with a spring in the usual manner.

The auxiliary frame 50 is provided with a central depending arm 52 to which is attached the end of a light coil spring 53 extending from a lug of the main work-support 40, said auxiliary spring tending to hold the auxiliary frame and oscillatory ridge-forming member in their depressed or lowered position upon the main work-support d0, This low position is determined by engagement of a part of the operating mechanism hereinafter referred to which is so arranged that while the independent lowering of the auxiliary frame upon the work-support is limited, said auxiliary frame and ridge-forming member can move to a lower depressed position when carried down by the depression of the work-Support either automatically in crossing thick parts of the work or when manually depressed for the insertion and removal of the work. This action and the operating mechanism for the periodic lowering of the ridge-forming member will be hereinafter explained.

|30 is the rigidly mounted presser-foot projecting forwardly from the under face of machine arm 5 to a position above the ridge-forming disk 60 and the work-supporting platens l0. The presser-foot is formed with the usual longitudinal slot into which a ridge of the work is pressed by the disk B0 for the action of the stitch-forming mechanism.

The shaft 6I has adjustably secured to it a downwardly presented crank arm 62 to which ia pivotally connected at 63, a link 64 in turn pivoted at 65 to one arm of a bell crank lever 61 pivotally mounted upon a screw bolt 68 secured to the machine frame. The other arm of the bell crank lever 61 is pivoted to the lower end of an eccentric link 69 having a yoke at its upper end encircling the eccentric I4 which is secured upon the shaft I0 alongside of the pulley II.

It will be observed that the work-supporting frame 40 projects rearwardly from the machine arm 6.

By the eccentric link connection between the power shaft I0 and the shaft 6| of the ridgeforming disk it will be observed that the forward stroke of the disk is effected by an upward thrust upon the rock-arm B2.

The looper mechanism of the machine is not involved in the present improvement and is not specifically shown, but it will be understood that the same form of looper is employed as has been used in the past in this Dearborn type of machine, the loo-per being indicated at 'I6 carried on the forward end of the looper rod 'I'I carrying on its rear end a yoke pivoted upon a sleeve which is freely journalled upon the crank-pin mounted in the angularly offset arm of the crank disk in the usual manner. This looper and its operating mechanism will be clearly understood from Dearborn Patent No. 1,467,570 dated September 11, 1923i.

The feed mechanism may be of the general type shown in Dearborn Patent No. 825,026 dated March 6, 1906, the specific structure of the same being immaterial to the present invention.

|25 is the longitudinally movable rocking feedbar actuated at its rear end by the usual eccentric (not shown) upon main shaft I0.

The arm 42 of the Work-supporting frame 40 engages an adjustable stop plate 42a pivotally mounted upon a bracket of machine arm 6 and held in place by an adjustable tappet screw 48 threaded through arm and carrying upon its outer end a milled head 49, see Figures 1 and 5. This part of the structure is the same as shown in Dearborn Patent No. 1,964,381, dated June 26, 1934.

The lower end of an arm 54 projecting from auxiliary frame 50 engages the vertical tappet member |0|a adjustably mounted on the short arm |0| of the work-controlling bell crank lever which is pivoted upon a set screw |02 threaded into a vertical face of the base frame rib la. The other or long arm |03 of said bell crank projects rearwardly from its pivot |02 and is formed in its rear end with a horizontal elongated slot |04 through which projects a bolt |05. A short rock-shaft |06 extends transversely of the machine below and parallel with the main shaft l0. This rock-shaft |00 is freely journalled in a suitable bearing |01 formed in the frame arm 2 just above the frame base i. The inner end of said rock-shaft carries a forwardly projecting rock-arm |08 which overlaps the rear end of arm |03. The forward end of rock-arm |08 has an elongated slot |00 in which engages the end of the bolt |05 which forms a jointed connection between parts |03 and |08. The bolt |05 is formed with an enlarged head adjacent to the bell crank arm |03 upon which is freely journalled a hand-operated cam lever H0. This mechanism is the same as set forth in the above-named Patent No. 2,000,929.

The hand lever H0 is formed with a cam peripheral surface, designed to operate upon the upper face of the base frame to shift the position of the interengaging arms |03 and |08 into inactive position and lock them in that position.

The rock-shaft |00 carries at its outer end an arm H5 having an anti-friction roller ||6 which operates in peripheral engagement with a controlling cam 'l mounted upon and rotating with a gear ||8 freely journalled upon a stub shaft H9 carried in the machine arm 2 beneath the main shaft I0. This gear ||8 meshes with and is driven by a smaller gear |20 keyed to the shaft I0 alongside of the eccentric link 09. The intermeshing gears ||8 and |20 may have any desired ratio such as 2:1, 3:1, etc., depending upon the number of impulses it is desired to impart to the system of levers which control the periodic movement of the auxiliary frame carrying the ridge-forming member upon the worksupport.

It will be observed that the engagement of anti-friction roller ||6 of lever |5 with the high portion of cam ||l rocks the long arm |03 of the work controlling bell crank to press upon the tappet arm 54 and slightly raise the ridge-forming member 00 by which the work is supported in the path of the needle. This position of the parts is illustrated in Figures 5 and 7, the needle in the stitching operation taking a deep bite in the work which, when operating upon a hem, will pass through the edge of the hem and the lower layer or base material. When the roller of rock-arm lili is in engagement with the low portion of cam the work support is in position to present the ridge-forming member 60 in a slightly lower elevation as shown in Figures 3 and 6, in which position the needle passes through a shallower bite of the material passing through the edge of the turned over layers and skipping the base material or making a blind stitch therein.

In Figures 3 and 6 of the drawings the ridgeforming member 60 is shown in its lowest position at the moment of penetration of the needle Il, the view showing the needle passing through the upper two layers of material a and b and missing the lower layer or base material c. In this position the mechanism is performing what is referred to as the skip-stitch. In Figures 5 and '7 the ridge-forming member 00 is'shown in its elevated position in which a bigger bite or ridge is formed in the work. In this position of the parts the needle |'l is represented as penetrating all three layers of the work, making a deep stitch. In the form of machine illustrated the ratio of the gears is such that two of the skip-stitches are formed between two adjacent deep stitches.

The spring 53 normally holds 'the auxiliary frame and ridge-forming disk 60 in low position upon the work-support. This low position is determined by the engagement of arm 54 with tappet arm liot. By adjusting the position of this arm l0 la upon the short arm I 0| of the operating bell crank lever the exact low position of the auxiliary frame can be determined. While the engagement of arms 54 and lla normally limits the low position of the auxiliary frame upon the work support it will be clear that said arms do not interfere with the free downward depressio-n of the work-support for inserting or removing work and to automatically take care of the passing of extra thickness like seams in the work.

The tappet arm |0|a may be adjustably mounted upon the arm 0| of the bell crank by any suitable means. As shown in the drawings this arm lilla is formed with a box-like housing embracing the arm |0| and pivotally mounted thereon by a machine screw lllb. An adjusting screw lille is threaded through one of the walls of the tappet arm housing and engages the arm |06 for accurately locating the tappet arm lilla with reference to the arm 54 of the auxiliary frame.

I claim:-

1. The combination, in a sewing machine, with a presser-foot, a driving shaft, a work-support beneath said presser-foot, and suitable workfeeding and stitch-forming mechanisms, of a uniformly oscillating ridge-forming member mounted for independent oscillation and bodily movement upon said work-support, and timed opera'fa ing mechanisms actuated by said shaft for periodically oscillating and bodily raising and lowering the ridge-forming member upon and independently of said work-support in timed relation to said stitch-forming mechanism, whereby successive deep stitches and intervening shallow skip-stitches are formed.

2. The combination, in a sewing machine, with a fixed presser-foot, a driving shaft, a yielding upon said work-support, a uniformly oscillating ridge-forming member mounted upon said auxiliary frame and movable bodily therewith independently of said work-support, and timed operating mechanisms between said shaft and said ridge-forming member and said auxiliary frame respectively for periodically oscillating and. bodily raising and lowering the ridge-forming member with relation to said presser-foot.

4. The combination, in a sewing machine, with a fixed presser-foot, a driving shaft, a yielding spring supported work-support beneath said presser-foot, and suitable work-feeding and stitch-forming mechanisms, of an auxiliary spring supported frame movably mounted upon said work-support, a ridge-forming member mounted upon said auxiliary frame and movable bodily therewith independently of said worksupport, the spring supporting said auxiliary frame being relatively more yielding than the spring supporting said work-support, and timed operating mechanism between said shaft and said auxiliary frame for periodically bodily raising and lowering the ridge-forming member with relation to said presser-foot.

5. The combinaiion, in a sewing machine, with a fixed presser-foot, a driving shaft, a yielding work-support beneath said presser-foot, and suitable work-feeding and stitch-forming mechanisms, of an auxiliary frame movably mounted upon said work-support, a uniformly oscillating ridge-forming member mounted upon said auxiliary frame and movable bodily therewith independently of said work-support, independent sustaining springs for said work-support and said auxiliary frame, and timed operating mechanisms between said shaft and said ridge-forming member and said auxiliary frame respectively for periodically oscillating and bodily raising and lowering the ridge-forming member with relation to said presser-foot.

LOUIS RIVERS. 

